1. Field of the Invention
The present invention is directed to catheters adapted for passage through the accessory channel of an endoscope into a duct or passageway within the gastrointestinal system of the body. Although not limited in its applicability and scope, the invention has particular applicability to procedures which involve the advancement of the catheter to positions within the biliary tract and especially to the practice of Endoscopic Retrograde Cholangiopancreatography.
2. Description of the Prior Art
A number of procedures have evolved in recent years using instruments intended to be inserted through an endoscope in various positions with in the gastrointestinal system for the purpose of diagnosis and for therapeutic procedures, including the insertion of stents, devices for the extraction of stones from the biliary duct, the removal of polyps and the extraction of tissue for biopsy purposes.
One diagnostic technique which has come into use is Endoscopic Retrograde Cholangiopancreatography (ERCP) which is described in copending application Ser. No. 07/880,842, filed May 11, 1992. The ERCP technique is an endoscopic technique which involves the placement of a side-viewing instrument within the descending duodenum. The procedure eliminates the need for invasive surgical procedures for identifying biliary stones and other obstructions of the biliary and pancreatic ducts. As background of the invention, the ERCP technique exemplified the problems and difficulties which the present invention addresses.
Utilizing this technique, the Papilla of Vater and common biliary duct are cannulated, contrast medium injected and pancreatic ducts and the hepatobiliary tree visualized radiographically or examined with a duodeno fiberscope. Skilled medical practitioners can visualize approximately 90-95% of the biliary and pancreatic ducts using this technique.
ERCP is typically performed on an X-ray table. During the procedure, the patient's oropharynx is anesthetized with topical lidocaine, and the patient is sedated intravenously with diazepam. Atropine and glucagon are given intravenously to relax the duodenal muscles.
The ERCP procedure has heretofore typically been performed by the endoscopic introduction of a single lumen catheter into the pancreatic and common biliary ducts of a patient. Such ERCP catheters have typically been constructed from Teflon. At times, a spring wire guide may be placed in the lumen of the catheter to assist in cannulation of the ducts. A stylet, used to stiffen the catheter, must first be removed prior to spring wire guide insertion. The introduction of the spring wire guide eliminates the ability to inject contrast medium or makes it highly cumbersome.
To summarize the procedure, an ERCP catheter is initially inserted through the endoscope and into the biliary or pancreatic ducts. If difficulty is encountered or if the operator so desires, a spring wire guide is threaded into the catheter to assist in the cannulation. After the catheter is inserted into the duct and threaded over the spring wire guide, the spring wire guide is removed. A radio-opaque contrast medium is then injected through the single lumen of the catheter in order to identify obstructions such as bile stones. Once located and identified, such stones can then be eliminated or destroyed by methods such as mechanical lithotripsy utilizing a device such as an Olympus BML-10/20 Mechanical Lithotriptor.
This method of performing ERCP has several disadvantages. Most notably, the process of withdrawing the stylet or spring wire guide in order to clear the single lumen for contrast medium or dye infusion frequently repositions the catheter. Thus, when the radio-opaque or contrast medium is injected into the catheter, the catheter is often improperly positioned for proper fluoroscopy or X-ray visualization. Moreover, this method presents the further problem of having to repeatedly remove the stylet or an approximately six foot long spring wire guide, maintain its cleanliness and then reinsert it into the catheter. In addition, the dye is sticky and reintroduction of the guide wire is made difficult due to the frictional resistance offered by it. Finally, single lumen catheters frequently experience the problem of back-flow in which the radio-opaque dye is squirted back out the side port of the catheter and onto the administering medical professional.
The above problems often result in the need to repeat the procedure and a time consuming exercise of trial and error. Multiple attempts at properly positioning the catheter and spring wire guide are often necessary. Increased amounts of tracer dye associated with multiple injections increase the risk of pancreatitis. Because the ERCP procedure is performed under sedation, the additional time required for proper catheter positioning tends to increase the risk to the patient. Furthermore, because of the considerable expense of maintaining a procedure room, the use of single lumen ERCP catheters can add considerably to the expense of the procedure. Accordingly, practice of ERCP procedures has heretofore been limited to only the most skilled endoscopists.